A conventional bicycle runs after a rider steps pedals, when riding with or a passenger a heavy object, the riders steps the pedals strenuously. When riding on an uphill, it is possible to break a chain because of excessive stepping force.
Furthermore, the chain drives a rear wheel to run, so it is easy to remove from a sprocket easily.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.